Back in the late '80s and early '90s my brother and I would run all over the parking lots while our mom was in the store, and return all the carts. We would see how big of a stack we could manage to get moving while we were at it. IIRC our record was 43 carts. We really wanted to hit 50, but I think that was just too much mass for us to handle.

I don't clear the lot anymore, but I do park out by the edge of a lot, if I brought my car, and pick up any carts on the way into the store.